The Inertia Driven® System: The Power Inside Stoeger Semi-Auto Shotguns
Inertia Driven System
The Inertia Driven® System powers the world’s fastest, simplest, and most reliable semi-auto shotguns.
The law of inertia has been harnessed in the Inertia Driven® System, making Stoeger semi-auto shotguns the fastest, simplest, and most reliable.
Newton’s first law of physics, regarding inertia, is consistent and unchanging. And we put it to work for you in the best operating system ever devised.
Reliable – The Inertia Driven System never needs adjusting. It will cycle anything from light field loads to 3-1/2” magnums with consistent reliability year after year.
Simple – The system has only three primary parts: the bolt body, the inertia spring, and the rotating bolt head.
Fast – With very few parts, the Inertia Driven System is fast.
Clean – Gas, smoke, and burnt powder stay in the barrel where they belong, instead of being channeled into the gun’s mechanism, as they are in gas systems.
Strong – Strong steel locking lugs on the rotating bolt head of the Inertia Driven System lock steel to steel inside the gun barrel.
Low-Maintenance – Gun cleaning takes a fraction of the time, since the system is cleaner.
Lightweight – The Inertia Driven System is incredibly lightweight. Shotguns designed with the system can be some of the lightest ever produced.
Perfect Balance – With no springs, action bar linkage, or heavy gas cylinders under the fore-end, Inertia Driven shotguns balance like a fine game gun should.
How the Inertia Driven System Harnesses the Law of Inertia
Step 1 Chambering
As the bolt assembly moves into battery, the locking head pin moves along a curved track in the bolt body. It rotates the steel bolt head into engagement with the steel barrel extension. The cartridge drop lever is down. The red dot indicates that the gun is cocked.
Step 2 Firing
When the trigger is pulled, every part of the shotgun except the bolt body moves rearward. The curved track in the bolt body is moving forward relative to the rest of the gun. The curved track presses against the locking head pin. This pressure turns the bolt head even more tightly into the barrel extension. At the same time, the inertia spring is compressed between bolt head and body. The cartridge drop lever moves up, allowing a shell to move from the magazine to the carrier.
Step 3 Recoil
Near the end of the recoil cycle, chamber pressure drops to a safe level. The gun’s rearward motion slows. The heavy inertia spring then thrusts the bolt assembly rearward. That action unlocks the rotating bolt head, extracting the spent shell from the chamber and pulling it against the ejector.
Step 4 Ejection
As the empty shell exits the receiver, the energy of the moving bolt assembly re-cocks the hammer and compresses the recoil spring in the butt stock. The recoil spring then thrusts the bolt assembly forward. This action lifts the oncoming shell into position and chambers a fresh cartridge. Within a fraction of a second, the gun is ready to fire again.
